High efficiency evacuated solar panel

ABSTRACT

Evacuated solar panel ( 1 ) comprises a frame ( 2 ) carrying spacers ( 3,4 ) crossing one another and one or two transparent walls ( 10, 10   a ) connected to said frame ( 2 ) and defining with said frame ( 2 ) an evacuated closed chamber ( 11 ). The chamber ( 11 ) contains the longitudinal and transverse spacers ( 3,4 ) and an absorber ( 14 ) comprising a plurality of absorbing panels ( 14   a,    14   b ) each connected to a cooling pipe ( 15 ) welded to the frame ( 2 ) at both extremities. The longitudinal spacers ( 3 ) are in contact with the transparent wall ( 10 ) to support it against the ambient pressure, while the transverse spacers ( 4 ) support the longitudinal sides of the frame ( 2 ) against the ambient pressure and are not in contact with the transparent wall ( 10 ), so allowing the absorbers ( 14   a,    14   b ) to cover the whole length of the panel ( 1 ) without interruptions.

The present invention relates to a high efficiency evacuated solar panel.

Existing designs of evacuated solar panels comprise a frame which contains spacers crossing one another which support two transparent glass walls or a glass transparent and a metallic wall.

The transparent walls define, with the frame, an evacuated closed chamber which contains the spacers and the absorber.

The spacers which cross one another support the transparent walls and create a number of cells, each containing an absorber element.

Each absorber element consists of a blackened flat metal surface which carries a cooling pipe.

During operation, the absorber elements collect the solar energy and heat the fluid circulating in the cooling pipes.

Due to the presence of the spacers the amount of solar energy which impinges the absorber is smaller than that which is theoretically possible.

In addition, the absorbers expand when heated; therefore in order to cope with this expansion, usually a greater clearance between the spacers and the absorber is required.

This further decreases the useful surface of the solar panels and thus also decreases the amount of solar energy which may be absorbed.

The technical aim of the present invention is therefore to provide a solar panel by which the said problems of the known art are reduced.

Within the scope of this technical aim, an object of the invention is to provide a solar panel able to collect a very high amount of the energy which impinges on it.

The technical aim, together with these and further objects, are attained according to the invention by providing a high efficiency solar panel in accordance with the accompanying claims.

Advantageously, the spacers of the invention also helps centering and supporting the cooling pipes.

Further characteristics and advantages of the invention will be more apparent from the description of a preferred but non-exclusive embodiment of the solar panel according to the invention, illustrated by way of non-limiting example in the accompanying drawings, in which:

FIG. 1 is an exploded schematic view of a solar panel according to the present invention;

FIG. 2 is a detail of FIG. 1 showing the spacers connected together.

With reference to the figures, these show a high efficiency evacuated solar panel indicated by the numeral reference 1.

The solar panel 1 comprises a frame 2 which carries longitudinal and transverse spacers 3, 4.

The longitudinal spacers 3 have their ends resting close to the frame 2, and the transverse spacers 4 have their ends welded to the frame 2 and are also connected to the spacers 3.

As shown in the enclosed drawings, the longitudinal and the transverse spacers 3, 4 cross one another.

In addition, the solar panel 1 of the invention also has two transparent walls 10, 10 a connected to the frame 2 which define with the frame 2 a closed chamber 11 containing the spacers 3, 4 and the absorber 14.

During manufacturing the chamber 11 is evacuated through a pumping flange in order to make an evacuated solar panel.

The absorber 14 comprises a plurality of absorbing panels 14 a, 14 b, each connected to a cooling pipe 15.

The longitudinal spacers 3 have a portion 17 in contact with the transparent walls 10 and 10 a to support them against the ambient pressure; on the contrary, the transverse spacers 4 are apart from said transparent wall and do not support it.

The transverse spacers are welded to the longitudinal sides of the frame and support them against the external ambient pressure.

In other words only the spacers 3 support the transparent walls 10, 10 a, while the spacers 4 are not in contact with the transparent walls 10, 10 a when the solar panel 1 is evacuated.

The absorber 14 a, 14 b extend between the longitudinal spacers 3, the transverse spacers 4 and the transparent walls 10, 10 a and are supported by the spacers 4.

The transverse spacers 4 have seats 22 housing the cooling pipes 15 of the absorber 14.

This structure allows the cooling pipes 15 to be centered and supported in an easy way.

The seats 22 of the spacers 4 are defined by recesses in the spacers 4 and preferably they also have protruding edges 23.

The seats 22 preferably have a spacer 27 in loose contact at their bottom to reduce the thermal contact with the cooling pipes 15.

Moreover, within the chamber 11 the solar panel 1 is provided with a getter pump to help keeping the vacuum.

Thus, the cooling pipes are welded to the frame at both extremities. The longitudinal spacers are in contact with the transparent wall to support it against the ambient pressure, while the transverse spacers are not in contact with the transparent wall, so allowing the absorbers to cover the whole length of the panel without interruptions.

FIG. 2 shows one possible connection between the longitudinal and the transverse spacers; in particular FIG. 2 shows the longitudinal and the transversal spacers which are connected at their crossings by a connection slidable along the longitudinal spacers.

The longitudinal spacers 3 have grooves 30 which are cross-shaped, preferably with the upper corners 32 between a longitudinal and vertical part of the cross-shaped grooves which are chamfered; alternatively, only one of the two upper corners 32 between a longitudinal and vertical part of the cross shape grooves is chamfered.

The transverse spacers 4 have opposite indented positions 34, 36, possibly also defined by protruding portions 38.

The transverse spacers 4 are inserted in the grooves 30 of the longitudinal spacers 3 and the indented portions 34, 36 of the second spacer 4 house edge portions close to the grooves 30.

This connection is not very tight and allows the longitudinal spacer 3 to slightly move vertically (while the transverse spacers 4 are fixed) to adapt to the pressure of the transparent walls; the connection also allows the longitudinal spacers 3 to slightly move longitudinally, to cope with their thermal expansion.

The operation of the solar panel of the invention is apparent from that described and illustrated and is substantially the following.

The longitudinal and transverse spacers 3, 4 are connected together and are inserted into the frame 2.

Thus the ends of the spacers 4 are welded to the frame 2, while the ends of the spacers 3 are free to move.

Afterwards the absorber 14 is assembled within the frame 2; in this respect the absorbing panels 14 a, 14 b (having a longitudinal length substantially equal to that of the chamber 11) with the cooling pipes 15 connected thereto are placed onto the transverse spacers 4, with the cooling pipes 15 inserted in the seats 22.

Thus the transparent walls 10, 10 a are applied on the frame 2 and the spacers 3, then the cooling pipes are welded to the frame 2 and the transparent walls 10, 10 a are fixed in a usual way.

Afterwards the vacuum is pulled within the chamber 11; the transparent walls 10, 10 a are thus supported by the frame 2 and the spacers 3, while the spacers 4 support the absorbing panels 14 a, 14 b via their cooling pipes 15.

In particular, as shown in the enclosed drawings, the side absorbing panels 14 a are housed in a cell having three sides defined by the frame 2, while the fourth side is defined by a spacer 3, and the central absorbing panels 14 b are housed in a cell having two short opposite sides defined by the frame 2, while the other two longer sides are defined by two opposite longitudinal spacers 3.

During operation the solar panel 1 of the invention has a very high efficiency, because it is provided with absorbing panels with a great surface, greater than the surface of a traditional solar panel having the frame of the same dimensions. Thus the solar panel of the invention is able to collect a great amount of the solar energy which impinges on it.

This spacers design allows the absorbers to cross longitudinally the panels without interruptions, this feature would not be possible with transverse spacers touching the transparent glass walls.

In this way the absorber surface is increased and the panel efficiency is improved.

During operation the longitudinal spacers may move to adapt themselves to the pressure exercised onto the transparent walls.

In particular temperatures cause deformations of the longitudinal spacers, nevertheless they do not alter their substantial rectilinear shape, because the ends of each longitudinal spacer are free to expand and there are provided a number of intermediate sliding connections along the longitudinal spacers (the connection with the transverse spacers which prevent transversal movements). In addition longitudinal spacers may also move in the vertical direction.

This design insures the required transverse rigidity but does not block the spacers longitudinally and vertically.

The embodiment described above is provided with two transparent walls, i.e. the transparent wall 10 and the transparent wall 10 a because it is preferably used in connection with mirrors reflecting the solar light on the back of the absorber.

A different embodiment (to be used without such reflecting mirrors) may have the wall 10 a made of a transparent wall (as the above described embodiment) or a metal wall.

It has been found in practice that the solar panel according to the invention is particularly advantageous because it has a simple structure and a high efficiency.

The solar panel conceived in this manner is susceptible to numerous modifications and variants, all falling within the scope of the claims. In practice the materials used and the dimensions can be chosen at will according to requirements and to the state of the art. 

1. High efficiency evacuated solar panel comprising a frame carrying longitudinal and transverse spacers crossing one another and at least a transparent wall connected to said frame and defining with said frame an evacuated closed chamber containing said longitudinal and transverse spacers and an absorber comprising a plurality of absorbing panel each connected to a cooling pipe, said longitudinal spacers having a portion in contact with said transparent wall to support it against the ambient pressure and said transverse spacers are apart of said transparent wall, said absorbing panels extend between said longitudinal spacers, transverse spacers and said transparent wall. Wherein said absorbing panels are supported by said transverse spacers.
 2. Solar panel as claimed in claim 1, wherein said transverse spacers have seats housing the cooling pipes of said absorber.
 3. Solar panel as claimed in claim 2, wherein said seats of said transverse spacers are defined by recesses in said transverse spacers.
 4. Solar panel as claimed in claim 3, wherein said seats also have protruding edges.
 5. Solar panel as claimed in claim 4, wherein said seats have a spacer in loose contact at their bottom to thermally insulate the cooling pipes.
 6. Solar panel as claimed in claim 5, wherein said absorbing panels have a longitudinal length substantially equal to that of the chamber.
 7. Solar panel as claimed in claim 6, wherein said absorbing panels of said absorber are housed in a cell having three sides defined by the edge of the frame, while the fourth side is defined by a longitudinal spacer.
 8. Solar panel as claimed in claim 7, wherein the central absorbing panels 14 b are housed in a cell having two short opposite sides defined by the edge of the frame, while the other two longer sides are defined by two opposite longitudinal spacers.
 9. Solar panel as claimed in claim 8, wherein the chamber of the solar panel is provided with a getter pump to help keeping the vacuum.
 10. Solar panel as claimed in claim 9, wherein said longitudinal and said transversal spacers are connected at their crossings by a connection slidable along the longitudinal spacers.
 11. Solar panel as claimed in claim 10, wherein the longitudinal spacers have grooves which are cross-shaped.
 12. Solar panel as claimed in claim 11, wherein said cross-shaped grooves are designed with at least one chamfered upper corner between a longitudinal and vertical part of the cross-shaped grooves.
 13. Solar panel as claimed in claim 12, wherein the transverse spacers have opposite indented positions.
 14. Solar panel as claimed in claim 13, wherein said opposite indented portions are also defined by protruding portions.
 15. Solar panel as claimed in claim 14, wherein the transverse spacers are inserted in the grooves of the longitudinal spacers and their indented portions house edge portions close to the groove.
 16. Solar panel as claimed in claim 15, wherein the transverse spacers are welded to the longitudinal sides of the frame and support them against the external ambient pressure. 